The utility model discloses a full-automatic wire tightener which comprises a left pawl, a left end fixed nut, a device wall, a middle end fixed nut, a right end fixed nut, a right end rotating nut, a right pawl, a left end rotating nut, a connecting nut, a clamping arm, a coil, a base, a motor switch and a high-power motor. The left pawl is installed at the left end of the device wall through the connecting nut. The left end fixed nut and the middle end fixed nut are installed at the left end and the middle end of the device wall. The right end rotating nut and the left end rotating nut are installed on the right pawl and the left pawl respectively. The clamping arm and the left end fixed nut are of an integrated structure and are installed on the other side of the device wall. An outer spline of a main shaft of the high-power motor and an outer spline of the coil are connected together. The other end of the high-power motor is installed on the base. The full-automatic wire tightener is high in automation degree, the labor intensity of workers can be greatly lowered, and meanwhile wires to be tightened can bear constant tension and the full-automatic wire tightener is safe, economical and reliable.